Copolymers from cycloolefins

Cross-metathesis of unsaturated polymers with polyalkenamers affords another versatile method of forming block copolymers from cycloolefins ... 

Copolymers of cycloolefins are readily obtained by catalytic copolyermization reactions under appropriate conditions. They can be random, block, or graft copolymers depending on the monomer reaetivity, catalyst nature, polymerization procedure, or reaction parameters and they may display physical and mechanical properties totally different from those of the corresponding homopolymers. 

Block copolymers can be obtained by copolymerization of cycloolefins of entirely different reactivities or by applying adequate sequential addition of the monomer. They also arise from cycloolefins and vinylic monomers, including linear olefins, in the presence of Ziegler-Natta catalysts [5] [Eq. (3)] or of metathesis catalysts. In the latter case it is usual to change the reaction mechanism to Ziegler Natta [6] and group transfer polymerization [7] or from anionic-coordina-tive to metathesis polymerization [8] [Eq. (4)]. 

Whereas copolymers of two or more cycloolefins via Ziegler-Natta polymerization are seldom reported [2], an abundant literature covers the copolymerization of cycloolefins with linear olefins using this type of catalyst. This mode of introducing one or more acyclic repeat units into the polymer chain formed from cycloolefins will effect drastic changes in the physico-mechanical properties of these polymers, enabling them to be applied on a large scale in various areas. 

Block copolymers from cyclooolelins have been prepared by various experimental techniques [52]. Some interesting methods use living ROMP catalysts, which allow ready synthesis of new products having controllable structures and properties. Other methods apply cross-metathesis between unsaturated polymers and/or polyalkenamers [3], polymerization of cycloolelins in the presence of unsaturated polymers [4], polymerization of two or more cycloolelins of quite different reactivities with classical ROMP catalysts [4], and copolymerization of cycloolefins with other monomers, effected by changing the polymerization mechanism from ROMP to anionic, cationic, Ziegler Natta, and group transfer, and vice versa [6-8, 52]. 

Within the past five years, commercial interest in metallocene catalyst components for the polymerization of olefins has increased enormously. Commercial production of a rising number of polyolefin types from different companies is creating a burgeoning and highly diversified demand for metallocenes. New brand names (e. g., Metocene (Basell), Elite (Dow Chemical), Engage (DuPont), Exact (ExxonMobil), Luflexen (Basell), Apel (Mitsui Chemicals), Borecene (Borealis), Finathene (TotalFinaElf), Topas (Ticona), just to name a few) characterize polyolefins such as PE, elastomers, PP, cycloolefin copolymers (COCs) and PS from metallocene-type catalysts [1-3]. 

In the present study PPO-AGE copolymers have been obtained using as initiators TIBA H20 and various cocatalysts, in a first step, and then grafted by ROMP with cyclooctene in the presence of Grubbs first-generation Ru catalyst, in a subsequent step. Future experiments will be directed at grafting other cycloolefins by ROMP onto PPO-AGE copolymer, and also at extending the same ROMP modification approach to copolymers prepared from epichlorohydrine-AGE and epichlorohydrine-PO-AGE. 

Copolymerization. Copolymers could be prepared from the mixtures of the norbornene derivatives. They could also be copolymerized with cycloolefins without polar group such as cyclopentene or cyclooctene. The formation of the copolymer was confirmed by elemental analysis, ir spectrum, thin layer chromatography(TLC) and differencial scanning calorimetry(DSC). 

Vinylic copolymers derived both from cycloolfins and from a cycloolefin and an acyclic olefin are known. These are obtained by using cationic initiators or anio-nic-coordinative catalysts of the Ziegler-Natta type. 

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